AfriGeneas Free Persons of Color Forum

I'm having some trouble with missing pieces to my husband's family tree, specifically with two of his great-great grandparents.
1.John Haywood Clemens (Aug 1855-1951, husband of Mary Celestia Mason). I assume he's a decendant of James and Sophia Clemens, but I can't find the missing generation(s). Is there a list somewhere of James and Sophia's children and grandchildren?
2. Alice Caston or Coston (2 Feb 1850- 15 Feb 1925) was the wife of Zebedee Bass (1841-1925). I was visiting the Bass and Clemens cemetaries in Longtown yesterday after Roane Smothers' lecture at the Garst Museum and think I remember seeing a Coston headstone, but I know nothing of her parents or grandparents....

Can anyone help me with missing information (names and birthdates... pictures would be wonderful) of the earlier family members? Thank you!